A sexual propagation for plants has been shown for some species to yield large numbers of genetically identical embryos, each having the capacity to develop into a normal plant. Such embryos must usually be further cultured under laboratory conditions until they reach an autotrophic “seedling” state characterized by an ability to produce their own food via photosynthesis, resist desiccation, produce roots able to penetrate soil, and fend off soil microorganisms. Some researchers have experimented with the production of artificial seeds, known as manufactured seeds, in which individual plant somatic or zygotic embryos are encapsulated in a seed coat. Examples of such manufactured seeds are disclosed in U.S. Pat. No. 5,701,699, issued to Carlson et al., the disclosure of which is hereby expressly incorporated by reference.
Typical manufactured seeds include a seed shell, synthetic gametophyte and a plant embryo. A manufactured seed that does not include the plant embryo is known in the art as a “seed blank.” Such a seed blank typically is a cylindrical capsule having a closed end and an open end. Synthetic gametophyte is placed within the seed shell to substantially fill the interior of the seed shell. A longitudinally extending hard porous insert, commonly known as a cotyledon restraint, may be centrally located within the synthetic gametophyte and includes a centrally located cavity extending partially through the length of the cotyledon restraint. The cavity is sized to receive the plant embryo therein. The well-known plant embryo includes a radicle end and a cotyledon end. The plant embryo is deposited within the cavity of the cotyledon restraint cotyledon end first and is sealed within the seed blank by at least one end seal. There is a weakened spot in the end seal to allow the radicle end of the embryo to penetrate the end seal.
There are automated processes available to mass produce manufactured seeds of the type described above. One such automated process is described in U.S. patent application Ser. No. 10/982,951, entitled System and Method of Embryo Delivery for Manufactured Seeds, and assigned to Weyerhaeuser Company of Federal Way, Washington, the disclosure of which is hereby expressly incorporated by reference.
Currently, embryos are manually plucked from a growing medium and are physically placed on the plate for retrieval and insertion into a seed blank. Although such manual processes are effective, they are not without their limitations. As a non-limiting example, such manual operations are both labor and time intensive and, therefore, expensive. As part of the process to produce large numbers of somatic embryos available for insertion in manufactured seeds, it is desirable to minimize the manual labor element from the process.